A bug screen can be made of metal wire, fiberglass or any type of fiber mesh. Its main purpose is to keep out bugs, other pests, leaves, debris, birds etc from getting into a building. Most houses have these screens on their windows which are helpful to keep out mosquitos. Aluminum and and fiberglass are the most common materials used for a bug screen. They can be professionally installed or
. you can find do it yourself kits at local hardware stores. For more information on bug screens go to http://en.wikipedia.org/wiki/Bug_screen